Aircraft display systems are used in many modern aircraft in order to assist the pilot in performing various tasks. Modern displays include near-to-eye (NTE) displays, such as head mounted displays (HMDs), which may form part of a pilot helmet; head-up displays (HUDs) and other types of display where the pilot is able to view the surrounding environment through the display itself.
Display systems may present “enhanced” information to the pilot using a vision system (VS). More specifically, vision systems allow for the presentation of information to the pilot that is otherwise not easily visible by the pilot. One such example of a vision system is an Enhanced Vision System (EVS). Enhanced vision systems typically overlay an image onto an environmental view seen by the pilot in order to present information to the pilot that would otherwise not be visible by the pilot due to, for example, low-light conditions or adverse weather conditions. Typically, the EVS overlays information onto a view of the environment external to the aircraft as seen by the pilot through the NTE display. Some examples of the types of information that can be presented to a pilot via an EVS include a night-vision image stream captured using an Infra-Red (IR) camera or a thermal image stream captured using a thermal imaging camera. The captured image stream of the EVS is overlaid on top of the environmental view seen by the pilot through the NTE display.
Another example of a vision system is a synthetic vision system (SVS). A synthetic vision system may overlay computer-generated images onto the environmental view of the pilot. These computer-generated images may be translucent, such that the pilot is able to view the external environment through the overlaid image whilst still having the benefit of the information presented by the computer-generated image. For example, the computer-generated images may present information about airport features (such as runway locations, aircraft building locations) or terrain features (such as hazardous or high-altitude terrain) to the pilot that may otherwise not be visible to the pilot due to, for example, poor visibility conditions. Still other types of vision systems are known, such as combined EVS/SVS vision systems.
In conventional vision systems, the overlaid images are typically monochrome. For example, in the case of an overlaid EVS image presenting night-vision images to the pilot, a green monochrome night-vision image may be overlaid on top of the environmental view seen by the pilot through the NTE display.
In some situations, color-based information shown in the pilot's environmental view may be used by the pilot to make a decision (for example, to allow the pilot to distinguish between runways lit by white lighting and taxiways lit by blue and/or green lighting). In these situations, the monochrome images overlaid by the vision system may obscure the color-based information presented to the pilot from these sources of color-based information, and the pilot may have to switch-off the vision system in order to obtain this color-based information.
Accordingly, it would be desirable to decrease the likelihood that color-based information is obscured by vision systems shown on an aircraft display. Other desirable features and characteristics will become apparent from the subsequent detailed description and appended claims.